Cotton shrinks, and that your dryer is too hot or running too long. Born in the late 80s, I think this was even a joke on sitcoms at one point (I have this vagu

Cotton shrinks, and that your dryer is too hot or running too long. Born in the late 80s, I think this was even a joke on sitcoms at one point (I have this vague memory of a husband pulling his favorite shirt out of the dryer and wearing it while it was still damp just so it wouldn't shrink), so it seems more like previously-common knowledge that was lost.